JP2012197350A - Hydrorefining method of heavy oil - Google Patents

Abstract

[PROBLEMS] To reduce the hydrorefining catalyst when hydrorefining is carried out using a mixed oil of atmospheric residual oil and / or vacuum gas oil and solvent desorbed oil (DAO) from which asphaltenes have been removed. Therefore, the present invention provides a method for hydrorefining heavy oil that suppresses deterioration of the hydrorefining catalyst and improves the economics of the process.
The hydrorefining catalyst comprises a combination of a demetallization catalyst and a desulfurization catalyst, the sulfur content in the demetallized oil after passing through the demetallization catalyst is 1.1% by mass or more, and the metal content is 30%. A demetallized oil having a mass of not less than 45 ppm and not more than 45 ppm by mass is obtained, and then the demetallized oil is passed through a desulfurization catalyst to suppress degradation of the hydrorefining catalyst, so that the sulfur content is 0.4 mass% The following hydrorefined oil can be obtained.
[Selection figure] None

Description

  The present invention relates to a hydrorefining method for removing sulfur content in heavy hydrocarbon oil in the presence of hydrogen.

In recent years, liquid fuels have been required to further reduce the sulfur content. In response to this demand, fuel oil manufacturers have already considered various clean fuel production methods. In particular, gasoline has restrictions on sulfur content of 10 mass ppm or less, so fuel oil manufacturers have taken countermeasures such as improving the catalyst and adding equipment.
In general, the main base material of gasoline is cracked gasoline produced by a fluid catalytic cracker (FCC). Therefore, in order to reduce the sulfur content in gasoline, it is important to reduce the sulfur content in cracked gasoline.
The sulfur content in the cracked gasoline depends on the sulfur content of the heavy oil (generally vacuum gas oil or atmospheric distillation residue) that is the FCC feedstock. The higher the sulfur content in the FCC feedstock, the higher the sulfur content of the cracked gasoline. Is known to be high. Therefore, in order to produce clean gasoline having a low sulfur content, it is necessary to previously remove the sulfur content in the heavy oil that is the raw material of FCC.
In the hydrorefining treatment (FCC pretreatment) for desulfurizing FCC raw materials, in a fixed bed reaction tower packed with a hydrotreating catalyst generally comprising a combination of a demetallization catalyst and a desulfurization catalyst, A process for hydrorefining heavy oil under high temperature and high pressure reaction conditions is performed. The sulfur content in heavy oil decreases as the hydrorefining conditions become more severe, and is therefore preferable for producing clean gasoline. However, because the hydrogenation reaction conditions are intentionally severe, or heavy oils with a high sulfur content are treated, if the reaction conditions become inevitably severe, the life of the hydrorefining catalyst will be shortened, resulting in the equipment being It is necessary to stop and refill the catalyst and restart hydrorefining. In such a case, the cost of the gasoline to be produced increases, which has a great adverse effect on the economy.
As described above, in the hydrorefining treatment of heavy oil, it is common to use a stack of a demetallization catalyst and a desulfurization catalyst. As a reason for this, it is considered that a demetalization catalyst is necessary in the previous stage in order to prevent deactivation of the desulfurization catalyst due to metal deposition. Non-Patent Documents 1 to 3 disclose examples showing the effectiveness of a demetallation catalyst.
In addition to metal deposition, there is coke deposition as a cause of degrading heavy oil hydrorefining catalysts. The cause of coke depositing on the catalyst is thought to be asphaltenes (paraffin-insoluble matter such as heptane) contained in the heavy oil of the raw material. Asphaltene is removed by solvent removal (SDA) treatment of the raw material before hydrorefining. It is disclosed in Non-Patent Document 4 that removal is effective for extending the catalyst life.

Studies in surface science and catalysis, 100, 171-180, 1996 (Elsevier) Fuel Processing Technology, 69, 229-238, 2001 (Elsevier) Journal of Petroleum Society, 44 (3), 147-153, 2001 (Japan Petroleum Institute) Applied Catalysis, 15, 197-225 (1985) (Elsevier)

SDA treatment of heavy oil using light paraffin such as propane, butane, pentane, etc. as solvent removes asphaltenes that cause coke degradation, so use solvent devolatilized oil (DAO) as part of the raw oil It has long been believed that the hydrorefining catalyst can be expected to have a long life. However, it has been found that the life of the hydrorefining catalyst cannot always be extended in a mixed raw material of atmospheric residual oil and / or vacuum gas oil and solvent desorbed oil (DAO) from which asphaltenes have been removed.
The purpose of the present invention is to increase the life of the hydrorefining catalyst and improve the economics of the process when hydrotreating the mixed raw material of atmospheric residual oil and / or vacuum gas oil and DAO. It is to provide a chemical purification method.

As a result of intensive investigations on the above problems, the present inventor has found that a mixed oil of atmospheric residual oil and / or vacuum gas oil and solvent debris oil (DAO) from which asphaltenes have been removed has passed through a demetallization catalyst layer ( It has been found that the life of the hydrorefining catalyst can be extended only when it satisfies a certain specific property, which is a raw material for a desulfurization catalyst, and the present invention has been completed.
That is, the present invention is as follows.

[1] A method of hydrorefining a feedstock obtained by mixing atmospheric residual oil and / or vacuum gas oil and solvent deasphalted oil, wherein the hydrorefining catalyst comprises a combination of a demetallation catalyst and a desulfurization catalyst, A demetallized oil having a sulfur content in the demetallized oil after passing through the demetallized catalyst of 1.1% by mass or more and a metal content of 30 ppm to 45 ppm by mass is obtained, and then the demetallization treatment A method for hydrorefining heavy oil, characterized in that a hydrorefined oil having a sulfur content of 0.4% by mass or less is obtained by passing the oil through a desulfurization catalyst.

[2] The heavy oil according to the above, wherein the ratio of the solvent desorbing oil in the raw oil obtained by mixing the normal pressure residual oil and / or the vacuum gas oil and the solvent desorbing oil is 30 to 90% by volume. Hydrorefining method.
[3] The reaction conditions for the above hydrorefining are: liquid space velocity is 0.1 to 0.8 h ⁻¹ , hydrogen / oil ratio is 3000 to 8000 scfb, reaction pressure is 10 to 18 MPa, and reaction temperature is 350 to 420 ° C. The method for hydrorefining heavy oil as described above, characterized in that it exists.
[4] The hydrogenation of heavy oil as described above, wherein the solvent-peeling oil is obtained by using a solvent in which at least two chain saturated hydrocarbons having 3 to 6 carbon atoms are combined. Purification method.
[5] The method for hydrorefining heavy oil as described above, wherein the volume ratio of the demetallization catalyst to the entire hydrorefining catalyst is 30 to 80%.

The present invention is described in detail below.
In the present invention, when hydrorefining a mixed raw material of atmospheric residual oil and / or vacuum gas oil and solvent desorbed oil (DAO), the life of the hydrorefining catalyst is extended, and the economical efficiency of the process is increased. The present invention relates to a method for hydrorefining oil.

The heavy oil used as the raw material used in the hydrorefining of the present invention is a mixed raw material of atmospheric residual oil and / or vacuum gas oil and solvent desorbed oil (DAO).
The atmospheric residual oil is the bottom fraction when petroleum-based crude oil, synthetic crude oil derived from oil sand, bitumen reformed oil, etc. are distilled in an atmospheric distillation tower, and the fraction having a boiling point of 343 ° C. or higher is 80% by mass. It is a heavy oil containing the above.
The vacuum gas oil (VGO) is a heavy oil containing 70% by mass or more of a fraction having a boiling point of 343 to 550 ° C. when the atmospheric residue is distilled under reduced pressure.
Solvent removal oil (DAO) is a bottom oil (heavy oil containing 70% by mass or more of a fraction having a boiling point of 550 ° C. or higher) obtained by distilling atmospheric residual oil under reduced pressure. A fraction obtained by extracting chain saturated hydrocarbons as a solvent. Examples of the chain saturated hydrocarbon having 3 to 6 carbon atoms include propane, normal butane, isobutane, normal pentane, isopentane, and normal hexane. In particular, it is preferable to combine at least two of these chain saturated hydrocarbons because the life of the hydrorefining catalyst tends to be long.

  The proportion of DAO with respect to the total hydrorefined mixed raw material is preferably 30 to 90% by volume, more preferably 40 to 80% by volume. If it is less than 30% by volume, the effect on the life of the hydrorefining catalyst tends to be eliminated, and the effect of the present invention tends to be reduced. On the other hand, if it exceeds 90% by volume, the life of the hydrotreating catalyst tends to be short, which is not preferable.

The hydrorefining catalyst in the present invention is used in combination of a demetallization catalyst (front stage) and a desulfurization catalyst (second stage).
A demetallation catalyst has a demetallation function and a desulfurization function, is a catalyst with relatively high demetallation activity, and a function of adsorbing metal components such as nickel and vanadium contained in feedstock oil under hydrorefining conditions It has mainly. The demetallation catalyst is, for example, a combination of active metal and Mo as a main component, and metals such as Ni, Co, and W using alumina or silica alumina as a carrier. Is 13 to 20 nm, the pore volume is 0.7 to 1.4 cm ³ / g, and the surface area is preferably 70 to 180 m ² / g. Typically, Ni-Mo and Ni-Co-Mo catalysts are mentioned.

A desulfurization catalyst has a desulfurization function and a demetallization function, is a catalyst having a relatively high desulfurization activity, and mainly has a function of removing sulfur and nitrogen contained in feedstock under hydrorefining conditions. .
The desulfurization catalyst is, for example, a combination of active metal and Mo as the main component, and metals such as Ni, Co, W, etc. using alumina or silica alumina as a carrier, and has a large surface area compared to the demetallation catalyst. Preferably, the average pore diameter is 8 to 12 nm, the pore volume is 0.4 to 1.0 cm ³ / g, and the surface area is 180 to 250 m ² / g. Typically, Ni-Mo, Co-Mo and Ni-Co-Mo catalysts are mentioned.

  There are no particular limitations on the shape of these hydrorefining catalysts, such as a prismatic shape, a cylindrical shape, a three-leaf type, a four-leaf type, and a spherical shape, and various shapes can be used. Moreover, although the size of these catalysts is not particularly limited, the particle size of the demetallation catalyst is preferably about 1 to 8 mm, and the particle size of the desulfurization catalyst is preferably 0.8 to 3.0 mm.

  The ratio of the demetalization catalyst to the entire hydrotreating catalyst is preferably 30 to 80% by volume, more preferably 30 to 60% by volume. If the demetallation catalyst is less than 30% by volume, the demetallation activity tends to be low and the desulfurization activity tends to deteriorate, which is not preferable. Moreover, when it exceeds 80 volume%, the desulfurization catalyst to be used decreases, desulfurization activity falls, As a result, in order to obtain the target sulfur content in produced oil, reaction temperature rises and the catalyst life tends to be shortened. This is not preferable.

  The demetallation catalyst and the desulfurization catalyst can be stacked and packed in the same reaction tower, or can be used by packing them in separate reaction towers. There is no limitation on the flow of the raw material oil to the reaction tower, and it may be upflow or downflow as long as it first passes through the demetallation catalyst layer and then passes through the desulfurization catalyst layer.

  Hydrorefining (demetallization and desulfurization) is performed after pre-sulfiding the packed catalyst. For the preliminary sulfidation, a method that has been used in petroleum refining so far, for example, a sulfidation method using a sulfiding agent such as hydrogen sulfide gas or dimethyl disulfide can be employed.

Liquid hourly space velocity of the hydrorefining (LHSV) is preferably from 0.1~0.8h ^-1, more preferably 0.15~0.60h ^-1, more preferably 0.2~0.5h ^-1. Less than 0.1 h ⁻¹ is not preferable because the amount of heavy oil treated is low and the economic efficiency of the process is lowered. On the other hand, if it exceeds 0.8 h ⁻¹ , the reaction temperature tends to be high and the catalyst life tends to be short.

  The hydrogen / oil ratio for hydrorefining is preferably 3000 to 8000 scfb (standard cubic feet per barrel), more preferably 3500 to 6000 scfb, and still more preferably 4000 to 5000 scfb. If it is less than 3000 scfb, the catalyst tends to deteriorate, which is not preferable. Further, even if it exceeds 8000 scfb, there is a tendency that the influence on catalyst deterioration is lost, which is not preferable.

  The reaction pressure for hydrorefining is preferably 10 to 18 MPa, more preferably 11 to 17 MPa, and further preferably 13 to 16 MPa. When the pressure is less than 10 MPa, desulfurization is difficult to proceed, and catalyst deterioration due to an increase in reaction temperature is likely to occur. On the other hand, if the pressure exceeds 18 MPa, an expensive pressure-resistant reaction tower is required, and the hydrogen consumption increases, which tends to deteriorate the economics of the process.

  The reaction temperature for hydrorefining is preferably 350 to 420 ° C, more preferably 370 to 410 ° C, and further preferably 380 to 400 ° C. When it is less than 350 ° C., the sulfur content of the target product oil tends not to be obtained, which is not preferable. On the other hand, if the temperature exceeds 420 ° C., the coking reaction becomes prominent and a differential pressure in the reaction tower tends to be generated.

  In the hydrorefining, the demetallation reaction and the desulfurization reaction may be performed under the same conditions as described above, or may be performed under different conditions. For example, in the case of a fixed bed apparatus in which the same reaction tower is filled with a demetallation catalyst and a desulfurization catalyst, hydrorefining is performed under the same conditions. In addition, when the reaction towers are separated and the demetallization catalyst is packed in the former reaction tower and the desulfurization catalyst is filled in the latter reaction tower, the respective reaction conditions can be performed independently.

The role of the demetallation catalyst in the present invention is important. Usually, the main purpose is to remove the metal components such as vanadium and nickel from the heavy feed oil to prevent the subsequent desulfurization catalyst from deactivating the metal. Therefore, it is preferable to remove a large amount of metal in the demetalization catalyst layer. However, in the case of using a feedstock obtained by mixing atmospheric residual oil and / or vacuum gas oil and solvent degreasing oil, the metal removal from the feedstock as much as possible is not performed by the demetallation catalyst. By adjusting the content of metal in the passed demetalized oil to a range of 30 ppm to 45 ppm by mass and making the sulfur content in the demetalized oil 1.1 mass% or more, hydrogen It has been found by the present inventors that the life of the chemical purification catalyst can be extended.
Therefore, in the heavy feedstock oil containing the normal pressure residual oil and / or the vacuum gas oil and the solvent deasphalting oil in the present invention, the metal content in the demetalized oil obtained by passing through the preceding demetallized catalyst layer The content needs to be 30 mass ppm or more, more preferably 31 mass ppm or more. When the metal content in the demetalized oil is demetalized to less than 30 ppm by mass, the reaction temperature rises in the operation in which the sulfur content in the product oil by the subsequent hydrorefining (hydrodesulfurization) is kept constant. This is not preferable because the catalyst life tends to be short. On the other hand, the upper limit needs to be 45 mass ppm or less, and more preferably 42 mass ppm or less. When the metal content in the demetalized oil exceeds 45 mass ppm, the reaction temperature rises in the operation in which the sulfur content in the product oil by the subsequent hydrorefining (hydrodesulfurization) is kept constant, and as a result, the catalyst life is shortened. Since it tends to be shorter, it is not preferable.

Moreover, the sulfur content in the demetallized oil obtained by passing through the previous demetallization catalyst layer is 1.1% by mass or more, and more preferably 1.2% by mass or more. When the amount is less than 1.1% by mass, the catalyst deterioration is advanced and the catalyst life tends to be shortened. On the other hand, the upper limit is preferably 2.2% by mass or less, more preferably 1.8% by mass or less, and further preferably 1.6% by mass or less. When the sulfur content of the demetalized oil exceeds 2.2% by mass, the reaction temperature increases in the operation in which the sulfur content in the product oil by hydrorefining is kept constant, and as a result, the catalyst life tends to be shortened. It is not preferable.
Here, the metal content is a value obtained by fluorescent X-ray analysis, and the sulfur content is a value obtained in accordance with JIS K2541 “Crude oil and petroleum products—sulfur content test method”.

  In the method for hydrorefining heavy oil of the present invention, in the case of using a raw oil in which atmospheric residual oil and / or vacuum gas oil and solvent debris oil are used, in the demetalized oil that has passed through the demetallized catalyst layer By adjusting the content of the metal in the range of 30 mass ppm to 45 mass ppm and the sulfur content in the range of 1.1 mass% or more, the life of the hydrorefining catalyst was extended and the sulfur content was sufficiently removed. The product oil can be obtained. The final product hydrorefined with the demetallation catalyst and the desulfurization catalyst has a sulfur content of preferably 0.4% by mass or less, and more preferably 0.3% by mass or less. If the sulfur content of the final product oil exceeds 0.4% by mass, the sulfur content in cracked gasoline obtained from FCC tends to increase, such being undesirable.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited to the following Example.

[Pre-sulfurization]
A flow-type fixed bed reactor having two reaction towers is charged with a predetermined amount of demetallation catalyst and desulfurization catalyst in separate reaction towers, and a mixed gas (hydrogen: hydrogen sulfide = 97: 3% by volume) is 30 L / hour. The reaction tower was heated from room temperature to 240 ° C. at a rate of 10 ° C./min at a total pressure of 15 MPa. Next, after maintaining at 240 ° C. for 4 hours, the temperature was raised to 340 ° C. again. The preliminary sulfidation was completed by maintaining at 340 ° C. for 24 hours.

[Catalyst stabilization]
After completion of the preliminary sulfidation, normal-pressure residual oil (boiling point 355 ° C. +, sulfur content 3.7 mass%, metal content 93 mass ppm) of Middle Eastern crude oil was kept at 340 ° C. in the reaction tower at a liquid space velocity of 0.2 h ^−1. Introduced in. Immediately thereafter, the reaction pressure was lowered to 12.7 MPa, and the reaction temperature was raised to 380 ° C. at a rate of 5 ° C./h. The oil passage was continued for 30 days under the condition of a hydrogen / oil ratio of 5000 scfb at 380 ° C. to stabilize the catalyst activity.

Example 1
Ni-Mo-based demetallization catalyst (average pore diameter 15 nm, surface area of 118m ² / g) packed 35ml and Ni-Mo desulfurization catalyst (average pore size 12 nm, surface area of 210 m ² / g) and 65ml in separate fixed bed reactor Then, after preliminary sulfidation under the conditions described above, the catalyst was then stabilized.
After stabilization of the catalyst, the normal pressure residual oil and the normal pressure were maintained while maintaining the reaction pressure, hydrogen / oil ratio, reaction temperature, and liquid space velocity (LHSV) at 12.7 MPa, 5000 scfb, 380 ° C., and 0.2 h ⁻¹ , respectively. Switch to raw oil (sulfur content 4.40 mass%, metal content 72 mass ppm) mixed with DAO obtained from solvent removal of rubutane (SDA) at 30:70 (volume ratio), sulfur content of final product oil The hydrorefining was carried out for 90 days while adjusting the reaction temperature so as to be 0.28% by mass. The reaction temperature at this time was the same for the demetallation catalyst layer and the desulfurization catalyst layer. The 90-day catalyst deterioration rate was determined as an indicator of catalyst life. The results are shown in Table 1. Moreover, the oil (first reaction tower outlet oil) that passed through the demetallization catalyst layer was collected about every 30 days, and the sulfur content and the metal content (Ni + V) were measured. The results are shown in Table 1.

(Comparative Example 1)
Presulfurization, catalyst stabilization, and hydrorefining were performed in the same manner as in Example 1 except that DAO was not mixed with the hydrorefining raw material. Table 1 shows the catalyst deterioration rate and the sulfur content and metal content of the oil that passed through the demetallization catalyst layer.

(Comparative Example 2)
Presulfurization, stabilization of the catalyst, and hydrorefining were performed in the same manner as in Example 1 except that the temperature of the demetalization catalyst layer was kept constant at 390 ° C. and only the temperature of the desulfurization catalyst layer was changed during hydrorefining. Table 1 shows the catalyst deterioration rate and the sulfur content and metal content of the oil that passed through the demetallization catalyst layer.

(Example 2)
A vacuum gas oil (VGO, boiling point 350 ° C. +, sulfur content 2.61 mass%, metal content 1 mass ppm) is used as a feedstock for hydrorefining instead of atmospheric residue, and VGO and DAO are 20:80 ( Presulfurization, stabilization of the catalyst, and hydrorefining were performed in the same manner as in Example 1 except that the raw material oil (volume ratio: 4.30 mass%, metal content: 51 mass ppm) mixed at a volume ratio) was used. Table 1 shows the catalyst deterioration rate and the sulfur content and metal content of the oil that passed through the demetallization catalyst layer.

(Comparative Example 3)
Presulfurization, catalyst stabilization, and hydrorefining were performed in the same manner as in Example 2 except that the temperature of the demetalized catalyst layer was kept constant at 385 ° C. during hydrorefining. Table 1 shows the catalyst deterioration rate and the sulfur content and metal content of the oil that passed through the demetallization catalyst layer.

(Example 3)
A raw material oil (sulfur content: 4.50 mass%, metal content: 57 mass ppm) mixed at VGO: DAO = 10: 90 (volume ratio) is used as a hydrorefining raw material oil, with an average pore diameter of 18 nm and a surface area of 106 m. Presulfiding, stabilization of the catalyst, and hydrorefining were performed in the same manner as in Example 2 except that ² / g of the Ni—Mo-based demetallation catalyst was changed to 50% by volume of the total amount of the catalyst. Table 1 shows the catalyst deterioration rate and the sulfur content and metal content of the oil that passed through the demetallization catalyst layer.

(Comparative Example 4)
Presulfurization, catalyst stabilization, and hydrorefining were performed in the same manner as in Example 3 except that the temperature of the demetalized catalyst layer was kept constant at 385 ° C. during hydrorefining. Table 1 shows the catalyst deterioration rate and the sulfur content and metal content of the oil that passed through the demetallization catalyst layer.

Example 4
Presulfidation, catalyst stabilization and hydrorefining were performed in the same manner as in Example 1 except that the pressure during hydrorefining was 15.0 MPa and the hydrogen / oil ratio was 4000 scfb. Table 1 shows the properties of the raw material oil, the catalyst deterioration rate, and the sulfur content and metal content of the oil that passed through the demetallization catalyst layer.

(Example 5)
Except for using DAO obtained from solvent removal by a solvent in which normal butane, normal pentane, and normal hexane were mixed at a ratio of 40:40:20 (volume ratio), presulfidation, catalyst Stabilization and hydrorefining were performed. Table 1 shows the catalyst deterioration rate and the sulfur content and metal content of the oil that passed through the demetallization catalyst layer.

  When hydrorefining the raw material mixed with atmospheric residual oil or vacuum gas oil (VGO) and solvent degassed oil (VGO) with a catalyst comprising a combination of a demetallation catalyst and a desulfurization catalyst, it passes through the demetallation catalyst layer. Only when the sulfur content in the demetalized oil obtained is 1.1 mass% or more and the metal content is 30 mass ppm or more and 45 mass ppm or less, the degradation of the hydrorefining catalyst is suppressed, and the final production A heavy oil having a sulfur content of 0.4% by mass or less can be produced.

  When hydrorefining using a normal pressure residual oil and / or a mixed oil of vacuum gas oil and DAO as a raw material, by using the method of the present invention, degradation of the hydrorefining catalyst is suppressed, so the economics of the process are reduced. Can be increased.

Claims (5)

  A method for hydrorefining raw oil obtained by mixing atmospheric residual oil and / or vacuum gas oil and solvent desulfurized oil, wherein the hydrorefining catalyst comprises a combination of a demetallization catalyst and a desulfurization catalyst, To obtain a demetallized oil having a sulfur content in the demetallized oil of 1.1% by mass or more and a metal content of 30 ppm to 45 ppm by mass, and then desulfurizing the demetallized oil A method for hydrorefining heavy oil, wherein a hydrorefined oil having a sulfur content of 0.4 mass% or less is obtained by passing a catalyst.   2. The heavy oil according to claim 1, wherein the ratio of the solvent desorbing oil in the raw oil obtained by mixing the normal pressure residual oil and / or the vacuum gas oil and the solvent desorbing oil is 30 to 90% by volume. Hydrorefining method. The reaction conditions of the hydrorefining conditions are that the liquid space velocity is 0.1 to 0.8 h ⁻¹ , the hydrogen / oil ratio is 3000 to 8000 scfb, the reaction pressure is 10 to 18 MPa, and the reaction temperature is 350 to 420 ° C. The method for hydrorefining heavy oil according to claim 1 or 2, characterized in that   The said solvent deasphalting oil was obtained using the solvent which combined at least 2 or more types of C3-C6 chain | strand saturated hydrocarbon, The any one of Claims 1-3 characterized by the above-mentioned. Method for hydrorefining heavy oil.   The method for hydrorefining heavy oil according to any one of claims 1 to 4, wherein the volume ratio of the demetalization catalyst to the entire hydrorefining catalyst is 30 to 80%.